Page 19 - CJO_DIABETES_ENG_W17

PATIENT CARE

The abducens nerve controls the lateral rectus. When paretic, the patient will also experience diplopia, but it will be
horizontal due to esotropia that is greater at a distance than at near. Sudden-onset CN6 palsy must be differentiated
from giant cell arteritis, myasthenia gravis, medial wall fracture, intracranial hypertension and thyroid (restrictive)
orbitopathy.

When the trochlear nerve is affected, the patient will experience diagonal diplopia, in this case due to involvement
of the superior oblique muscle. CN4 palsy also results in small torsional rotation of the eye. Patients with this con-
dition often learn to adopt a head-tilt to compensate. Differential diagnoses include multiple sclerosis, aneurysms,
intracranial hypertension, head trauma and tumours.

Diagnosis of Ocular Complications of Diabetes Mellitus

In the provision of primary eye care, the optometrist plays a crucial role in detecting ocular manifestations of sys-
temic disease, including diabetes. Particularly when the patient and optometrist have a long history together, chang-
es in both ocular structure and ocular function can be observed over time. The following recommendations for the
optometric examination of diabetic patients should facilitate the detection of potentially sight-threatening diabetic
eye disease.

OPTOMETRIC EXAMINATION OF A PATIENT WITH DIABETES
When examining a patient with diabetes, optometrists should consider the following elements of the patient’s med-
ical history: 138

1. Type and duration of diabetes: type 1, type 2, or gestational (self and family)
2. Current diabetes treatment (diet, oral medications, insulin type and dosage)
3. Blood sugar and glycemic control (including most recent fasting (spot) and A1c values)
4. Level of compliance with blood glucose control
5. History of diabetic retinopathy: date of diagnosis, level of severity, and treatments
6. Blood pressure and cholesterol/lipid status and treatment
7. Presence of co-existing kidney disease: note glomerular filtration rate (GFR)
8. Presence of peripheral or autonomic neuropathy

Optometrists should be active participants within a multidisciplinary health care team including, but not limited to,
the primary care physician, diabetes educator, nutritionist, endocrinologist and nephrologist.

ENTRANCE TESTING
Habitual and best-corrected (or pinhole) visual acuities should be assessed, with special attention paid to any re-
duction in best-corrected acuity and refractive shifts that may be attributable to fluctuations in blood glucose. Pupil
assessment may reveal sluggish responses, and ocular motility may be impacted by cranial nerve palsies involving
CN3, CN4 and CN6. Confrontation visual field testing may reveal peripheral constriction, particularly if there is a
history of panretinal photocoagulation.

ANTERIOR SEGMENT EXAMINATION
Slit lamp biomicroscopic examination of the anterior eye may reveal signs of dry eye syndrome or corneal defects
indicative of poor wound healing. Careful examination of the iris is necessary to rule out neovascularization of the
iris (NVI) and gonioscopy may be required if there is suspicion of new vessel growth involving the angle, raising the
risk of neovascular glaucoma (NVG). Regular tonometry will reveal any changes in intraocular pressure. Examina-
tion of the crystalline lens is important, as patients with diabetes frequently develop posterior subcapsular, cortical,
nuclear, and, more rarely, snowflake cataracts. Snowflake cataracts consist of gray-white opacities reminiscent of
snowflakes.
139
DILATED FUNDUS EXAMINATION
Stereoscopic slit lamp funduscopy through a dilated pupil is essential for the detection of diabetic retinopathy,
including DME, which is the most common cause of vision loss in diabetes (see Section 3: Diabetic Retinal Dis-
ease). The use of mydriatic agents is generally safe unless contraindicated by a high risk of angle closure. The high
magnification afforded by direct ophthalmoscopy may be helpful in the detection of NVD, but its clinical utility is

CANADIAN JOURNAL of OPTOMETRY | REVUE CANADIENNE D’OPTOMÉTRIE VOL. 79 SUPPLEMENT 2, 2017 19